Lattice Dynamics of Bi1.9Dy0.1Te3 Topological Insulator

• Published in: Physica. B, Condensed matter Vol. 640; p. 414050
• Main Authors: Ghosh, Labanya, Gangwar, Vinod K., Singh, Mahima, Kumar, Satya Vijay, Dixit, Srishti, Verma, Abhineet, Sharma, Durgesh Kumar, Kumar, Sudhir, Saha, S., Ghosh, A.K., Chatterjee, Sandip
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-09-2022
• Subjects: Density functional theory; Raman spectroscopy; Thermal conductivity; Thermoelectric; Topological insulators; Thermal conductivity; Density functional theory; Thermoelectric; Topological insulators; Raman spectroscopy
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2022.414050

In this report, we have investigated the Density functional theory (DFT) calculation, temperature-dependent thermoelectric power and Raman spectroscopy of Bi1.9Dy0.1Te3 topological insulator (TI). In this system, discrepancy due to the rare earth ion Dy initiates a Red-shift in Raman active modes in the Bi2Te3 TI. Here, the lattice thermal conductivity (κL) was evaluated in the Umklapp scattering limit using the temperature dependency of the vibrational phonon modes and was used to evaluate the Figure of merit (ZT) of the system. It has been demonstrated that the estimated Power factor and ZT is very large, confirming the efficiency of Bi1.9Dy0.1Te3 for better thermoelectric and electronic applications. Such immense thermoelectric power value of the corresponding system was further supported by the DFT calculation.
•The temperature dependency of the phonon dynamics in Bi1.9Dy0.1Te3 is described by the anharmonicity of phonon-phonon interaction.•Thermoelectric measurement demonstrated a higher value of the Seebeck coefficient (207 μV/K at 300 K) and enlarged power factor (5.13 × 10−3 W/K2m).•Using the Umklapp method, the lattice contribution of thermal conductivity was determined as 1.1095 W m−1K−1further determining total thermal conductivity.•The figure of merit was evaluated as 0.7764 using the values of Seebeck coefficient, thermal conductivity and electrical conductivity at 300 K.•The large power factor and Figure of merit have been supported by DFT calculation.